Protective coating



wan x. LEWIS, or mwm, massacnusn'rrs, ASSIGNOR :ro s'rannum OIL DEVELOPMENT COMPANY, a conronmrrou or DELAWARE PROTECTIVE COATING N 0 Drawing.

The present invention relates to protective coverings and more specifically to a protective coating for metals exposed to the action of petroleum or petroleum vapors. My invention will be fully understood from the following description.

Oil tanks used for the storage of crude and partially refined oils are subject to extremely severe conditions of internal corrosion, particularly when used for storage of high sulphur-containing oil such as are produced in Vest Texas fields and in other localities. Tank roofs, the upper plates, and the internal braces are quickly corroded, presumably by the combined efiects of the oil or oil vapor, moisture, and the sulphur-containing impurities in the oil.

I have invented a new type of protective coating which is cheap, resistant, and easily applied and by its use the life of tank roofs and other metal parts may be greatly extended. The coating is made up essentially of two parts, a first layer which is substantially impermeable to moisture, but which is more or less rapidly effected by oil or Bil vapors and a second coating applied'over the first which is substantially impermeable and unaffected byvoil, oil vapor or its corrosive impurities, and is substantially insoluble in water.

The metal surface to be covered is first preferably cleaned by scraping in the usual manner and removing rust spots. The first coating is then applied and is preferably one or more coats o a good oil pant, such as a lead paint or'zinc paint. Mixed base paints may also be used and particularly those containing fine divided metals such as aluminum or bronze.

After the paint has dried thoroughly the second coating is applied. This comprises a glue composition 'which containsa suitable fixing agent adapted to render the glue water insoluble. A' good quality hide glue is preferable because of its cost and durability, but bone glues or fish glues may be used as well. A small percentage, say to 2% of paraaldehyde is added to the glue solution as the fixing agent, although formaldehyde, tannic acid, potassium bichromate or the like may Application filed April 1,

be used. It may be preferable to apply the glue and later treat the surface with the fixing agent either in aqueous solution or as a gas in the use of formaldehyde. In any case, it is generally advisable to add 20 to of glycerine in the weight of thedry glue. and to also add a small quantity, say 4 to of oxalic acid to prevent too rapid hardening.

The glue is made up in a thick solution with water which may be heated and it is diluted to the proper consistency for brushing or spraying. For brushing two pounds of dry glue per gallon of water has proved satisfactory altho it may be varied considerably. For spraying generally more dilute solutions are preferable.

Instead of applying the glue as a solution directly to the painted metal, paper or other suitable absorbent fabric, preferably of a vegetable. nature maybe impregnated with the solution and after it has dried the fabric may be applied to the minted metal either by glue or other adhesives such as rubber cement, or bitumen or by suitable mechanical means. It may be advantageous in some cases to apply a glue solution over the impregnated fabric to fix the glue as heretofore specified.

While good quality paint is preferable for the first coating cellulose esters or others such as nitro-cellulose or cellulose acetate may be used in an appropriate solvent. Gums, resins, bitumen and the like may also be added to the paint to increase its effectiveness or asphalt or bitumen may be used instead of a drying oil paint.

' My invention is not to be limited by any theory of the manner in which my improved 2 aaoaaoa tially impervious to moisture, and applying a surface coating of animal glue to the coating of paint.

2. The method of protecting oil containers used for the storage of crude and artially refined oil from deterioration, whic comprises coating the body with paint substantially impervious to moisture, applying a surface coating of animal glue to the coating of paint, and treating the surface coating with a fixing agent adapted to chemically render the glue insoluble in water.

3. An article of manufacture impervious to corrosive action of oil, oil vapor or its corrosire impurities, comprising a metallic body portion, a layer of water proof paint, and a surface coating of animal glue.

4. An article of manufacture impervious to corrosive action of oil, oil vapor or its cor rosive impurities, comprising a metallic body portion, a layer of water proof paint, and a surface coating of animal glue insoluble in water.

5. The method of protecting the internal structure of oil containers used for the storage of crude and partially refined oil from corrosives, which comprises coating the structure with paint substantially impervious to moisture, ap lying a surface coating of animal glue to tl ie coating of paint, and treating the surface coating with a fixing agent adapted to chemically render the glue insoluble in Water. WARREN K. LEWIS. 

